Dual-action photocatalyst: MnO₂/CuO decorated 3D porous carbonaceous matrix as reusable photocatalyst for rapid removal of industrial dyes and antibiotics from contaminated-water

This study focuses on fabricating a dual-active photocatalytic cartridge material for degrading dyes and antibiotics. Hence, the in-situ uniform growth of MnO2/CuO on 3D porous high surface area carbonaceous matrix, not only efficiently degrades Eriochrome Black T (EBT - 95.40 %), Loffler's Methylene Blue (MB - 98.06 %), and azithromycin (96.50 %) within 100 min of light illumination but also reusable and stable upto 6 cycles. The mechanistic understanding based on band structure analysis, electron paramagnetic resonance technique and scavenging experiments, cumulatively explains about the participation of hydroxyl radical (•OH) at valence band of MnO2 (VBMO) and superoxide radical (•O2-) at conduction band of CuO (CBCO) in redox reactions following a Z-scheme mechanism. The theoretical studies show that the charge redistribution creates a built-in electric field between CuO-CNT-MnO2 layers, driving photogenerated electrons and holes in opposite directions, forming •O2- at CBCO and •OH at VBMO, thus enhancing degradation kinetics. The toxicity study shows 100 % cell viability with 100 minutes of dye-degraded water, 100 % bacterial viability, and healthier plants when exposed to azithromycin-degraded water, overall indicating that the degraded products are bio-compatible. A sustainable and smart prototype filter technology is demonstrated, which effectively filters 5 litres of dye/antibiotic under continuous light irradiation.